DESCRIPTION The overall goal of this proposal is to examine putative molecular mechanisms associated with cocaine-induced effects on the N-methyl-D- aspartate (NMDA) subtype of glutamate receptor. Administration of cocaine is reported to alter the expression of the NMDA receptor subunit, NR1, in a regionally specific manner. Recent methodological developments now provide the means to examine cocaine-induced effects on the NMDA receptor complex with increased specificity thus enabling a more comprehensive assess of changes in protein expression. The specific aims of this proposal are: 1) to characterize cocaine-induced changes in the expression and localization of NMDA receptor subunit and splice variant proteins-- including potential withdrawal time-dependent differences, 2) to further explore the relationship among neuronal nitric oxide synthase (nNOS), calmodulin (CaM), and NMDA receptor subunits for putative mechanisms associated with cocaine-induced changes in NMDA receptor expression, and 3) to assess alteration in NMDA receptor function associated with cocaine treatment as measured by nNOS activity. Changes in CaM, nNOS, and NMDA receptor subunit and splice variant expression will be investigated using immunohistological techniques. Immunoprecipitation will be used to evaluated possible cocaine-influenced disruption of CaM, nNOS and NMDA receptor interaction. Cocaine-induced changes in the function of NMDA receptors will be assessed using a nNOS activity assay. Findings will be important for understanding the molecular and neuroanatomical bases for drug effects on neurotransmission and synaptic organization, and may additionally contribute to therapeutic developments.